Cathode ray tube oscillator



Patented Ja n. l, 1935 UNITED STATES "PATENT oral-or.

. S CATHODE RA! TUBE OSCILLATOR Clarence W. Hanseli, Port Jefferson,

signor to Radio Corporation of America, a corporation of DelawareApplication January 3, 19:0, serm No. new

9 0lalms. (01. 260-313)- I My present invention relates to oscillators,and, more particularly, to oscillator circuits emmethod of, and meansforeliminating tube noises in the final output of high frequency entubenoises occur because of actual irregularities in the rate of emissionofv electrons from the tubecathodes; the method disclosed permittinggreater radio frequency amplification to be used so that smaller valuesof radio frequency energy could. be amplified successfully, Briefly, my,

above mentioned patent discloses an amplifier circuit which comprises anelectron discharge tube. including a cathode, a. plurality of anodeselectrostaticallyshielded from the cathode, the anodes being connectedin such a manner that variations in emission from the cathode result inequal and opposite variations in the anode output circuit whereby thedisturbing anode currents balance out and no noise is presentin theoutput'of the amplifier.

vNow,.1[ have found that this novel cathode tube lends itself verysatisfactorilyto operation in an oscillator circuit, so that it is notnecessary to supply an additional type of tube to be used as anoscillator in equipment where an oscillator i in .a heterodyne orsuper-heterodyne type of radio receiver.

Accordingly, it is one of the main objects of the present invention toprovide an oscillator circuit which permits the use of the novel formkinds of equipment, and the oscillation 'frequency of which circuitmaybe controlled by. 4'6 piezo-electric means, a resonant long line, oran- 1 50 rendered stable with regard. to its oscillation frenquency, thefrequency stabilizing means beingautomatic in its action. I 1 r o Otherobjects of the invention are to improve generally the efllciency ofoscillation circuits em- 55 bodying cathode ray tubes, and to, further,pro

ergy'amplifiers, it being understood that such No. 1,850,104, supra,

is required as well as amplifiers, as, for example,

' of'cathode ray tube so that a minimum numj ber of types of tube may beemployed in certain vide a tube which is durable and reliable inoperation, possess a high power output, a minimum of undesired reactionbetween the electrodes of the anode circuit'and the electrodes of theinput a frequency stable oscillatory circuit.

The novel features which I believe to be char acteristic of my inventionare set forth in particularity in the appended claims. The inventionitself, hbwever, as to both itsorganization' and methodof operation willbest be understood by reference to the following description taken inconnection with the drawing in which I have indicated diagrammaticallyseveral circuit organizations whereby my invention may be carried intoeffect.

In the drawing, I 7

Fig. 1 diagrammatically shows an oscillatory circuit embodying theinvention.

Fig. 2 shows an oscillation circuit employing an a modified form offrequency stabilizer.

Referring now to the accompanying drawing in which like referencecharacters indicate the same parts in the different figures there isshown in circuit, andwhich may be readily arranged in 6 Fig. 1, acathode ray tube ofthesame construction'as disclosed in' myaforementioned Patent wherein the tube is I de-- scribed ingreat detail.Accordingly, I will, in this application, confine myself to essentials nessary only for a clear understanding of the presso ent employment ofthe tube. The tube cathode 1 is heated by a source A, the resultingelectron stream 20 therefrom, passing between a pair of elongatedelectrodes 13. 13'. I

A pair of anodes 9, 9' .aredisposed within the :6 tube, andelectrostatically shielded from the cathode and control electrodes by ascreen grid electrode 10. The latter is supported by a metal- .lic,cylindrical envelope 11, the envelopebeing ailixed to a metallicdisk-like support and shield 14.- The anodes are energized from a source28, p v the positive terminal of the latter being connected to the anodecircuit, the latter including the I inductance 20' and the variablecapacity 21 shunted across the lattenwhich circuit connects thej'anodesin push-pull fashion.

A second metallic, cylindrical envelope 32 8111':-

rounds the control electrodes 13, 13'. and is negatively biased by meansof a lead 18 from the source D, the function of the envelope being toconcentrate the electronic stream 20 issuing from tlie cathode 1. \T hscreen grid 10 is positively biased through a lead 19 and me'mber 14,from.

a source it. .The control electrodes 13' and 13 an connected in seriesthrough an inductance 31,

' connected to any useful load may be coupled to v line type offrequency control is as follows: The

2 the midpoint of the latter being tapped and connected through a lead32 to the negative terminal of source C, it being noted that the sourcesD, C, E, and B are connected and grounded between the positive terminalof source and the negative terminal of source E.

m order to feed back energy from the output circuit to the input circuitthe inductance 20' is coupled to the inductance 31. Itwill, be notedthat this inductive coupling will be the only source of feedback;inasmuch as there is no possibility of feedback occurring within thetube due to the electrostatic shield 10. By varying the condenser 21, itis of course, possible to vary the oscillation frequency of the circuit.A coil 40,

the inductance 20' for utilizing the'oscillations set up in the anodecircuit of the tube.

The tube, arranged as shown inFig. 1, constitutes an initial source ofoscillations. To stabilize its frequency piezo-electric crystal means,generally designated as 41, may be connected in the input circuit, inshunt with the inductance 31. The stabilizing action of the crystaliswell known to those skilled in the art.

Again, the long line type of frequency control employing a resonant linemay be employed. This'type of control is shown and-claimed in myapplication Serial No. 400,489 gfiled October 18, 1929, now Patent No.1,945,546 granted February 6, 1934. I have therefore shown the resonantlong line type of frequency control in Fig. 1, in diagrammatical manner,as comprising a pair of electrical conductors 50, 51 each of which hasone end connected to one side of the inductance 31. A shunting conductor52, adjustable in the direction of the arrow, is adapted to vary thephysical length of the two conductors. A capac ity 53 should preferablybe shunted across the inductance 31 for rendering the input circuit morereadily susceptible to resonance, phenomena.

- While the crystal control will ordinarily be employed independently ofthe resonant line control, they may be employed in combination, ifdesired. Briefly, the operation of the resonant long long, resonant line59, 51, 52 acts as a sharply tuned circuit having substantiallyuniformly distributed inductance and capacity. Standing waves are builtup on the line giving it .an equivalent input reactance which isdependent solely upon the frequency, the length of the line, andindependent of any reaction caused by external circuits or loads. Thesestanding waves producedon the line,

an; applied to the oscillating tube .for controlling t nant circuit topull the oscillator into step therewith.

Again, the line may be considered to act 'as a phase shifter, .wavesfrom the oscillator being sent over to the line to the farend andreflected back to the oscillator, arriving back with a phase whichshifts rapidly with changev of frequency and which tends to modify theoscillator frequencyto make zero difference in phase between theingoingand reflected waves at the input end of the line. That is to say, thelong line acts to pull the oscillator into phasewith its own asciliations whenever there is a shift in phase caused-bye. shift in theoscillator frequency.

- The output from the anodes 9, 9' being connected, as shown, inpush-pull manner, it therefore results that the equal variations intheisaheated by source C.

I e frequency of the latter. Thus, the long line acts as a very sharplytuned reso- Y occurring at points 54, 55 will appear on the conodecurrents due to the usual source of tube noise will balance out, and nonoise will be transmitted with the useful'signals. 1

InFig. 2, I have shown an oscillatory circuit employing a cathode raytube, as in Fig. 1, the circuit being modified, however, for frequencycontrol by a long line of the. aperiodic, impedance matched type. Thelatter type of' control has been described, in detail, andfclaimed by J.L. Finch and J. W. Conklin'in application Serial No. 363.660 filed onMay 16, 1929.

In adapting this type of long line control to the present cathode raytube oscillation circuit, the'input and output circuits are tuned by thevariable capacities 53 and 21 respectively.

As in Fig. 1, the anodes 9, 9' are connected in push-pullto the sourceB. The, cathode is negative terminal of source C is connected through aresistance R, to the midpoint of the inductance 31, the the controlelectrodes'13, 13'. The resistance R is shunted by a radio frequencyby-pass capacity 60. A pair of series connected capacities 61, 62 areconnected across the cathode and their midpoint grounded for by-passingradio frequencycurrents to ground so-that no radio frequency voltagewill appear onthe cathode. I

The source D negatively biases the envelope 22, the positive terminal ofthe source D being connected to ground, the positive terminal of thesource C, and the negative terminal of source E also being grounded. Theinductance 31 leadjustably tapped by two electric conductors .50, 51, asat 50', 51, on either side of the midpoint connection. The oppositeterminals are con-' nected to the anode inductance 20', as at 54, 55,through capacities 56 and '7, on either side of the source 3 midpointconnection.

Briefly, the operation of this type of control is latter being .inseries withthe latter also serving to negatively bias both controlelectrodes. The

as follows: For the production of sustained oscillations by means of thecathode ray tube it will be necessary that the control electrodes 13 and13' and anodes 9 and 9' fluctuate in potential 180 degrees out of phasefor a desired tionship for the production of stable sustainedoscillations, a long lineis connected from the points 54 and frequency.In order to cause this phase rela- 55in the output circuit of the tubeto points and 51" in the input circuit thereof.

. By making the long line an odd number of half wave lengthslong at adesired frequency,

or by making it an even numberof half wave lengths long and reversingthe connections at I one end, it will be seen that potential variationstrol electrodes 13, 13' a certain period of time later, because of thetime required to travel over the lines 50, 51 so as to be opposite inphase to potntial fluctuations, occurring at points 54, 55. For anyother frequency of potential fluctuationsthe lines 50, 51 will not be ofthe coriect.

amplified to any desired extent bythe suitable choice of the values forthe electrical elements involved so that either regenerativeamplification or sustained oscillations results. The anode output of thetube may potential is kept from the control electrodes by means of theblocking condensers 56, 57. The

taken from an inductance 40 which is inductively coupled to the outputinductance 20', the coil it) being connected to any utilizing circuit.In order to prevent reflection, the line and 51 are tapped on in-.ductance 31 at points which cause the llnes'to be terminated by animpedance R, in the form of a resistance, corresponding in value to thesurge, or characteristic impedance of the lines The exact frequency'forwhich the circuit oscillates readily and with maximum efilciency andstability is obtained is adjusted by varying the lengths of the line 51,50. While I have indicated and described several systems for carrying myinvention into eflect, it will be apparent to one skilled in the artthat my invention is by no means limited to the particular organizationsas well as in the apparatus employed, may be made without departing fromthe scope of my,

invention as set forth in the appended claims. In .particular I wish topoint out that the detail .proportions and construction of the cathoderay shown will undoubtand an output circuit'connected to said anodes,

both circuits being tuned oscillations,

to the frequency of the means for regeneratively coupling the input andoutput circuits together externallyand a plurality of anodes,

. the input of said tube, means for preventing feed-back inside saidtube, and means for stabilizing the frequency of the oscillati'om bycoupling to the input circuit only of the oscillator a piezo- 2. Anapparatus for producing electrical oscillations comprising a cathode raytype of vacuum tube having a plurality of control electrodes meansfor-suitably applying direct current potentials to the controlelectrodes and anodes ofthe tube, input and output circuits each tunedto the frequency of the oscillations,

and output circuits. and means independent, of said output circuitcomprising a sharply tuned resonant transmission line circuit'on whichstationary electromagnetic waves are allowed to develop coupled to theinput circuit of said oscillator for stabilizing the frequency of theoscillations, and a utilization circuit coupled tosaidoutput circuit.

3. n a paratus for producing electricaloscillations comprising a cathoderay type of vacuum tube having a cathode, a plurality of control.electrodes, and a plurality of anodes,

- means for applying a negative potential to said control electrodes anda positive potential to said anodes with respectto the cathode of saidtube, input and output circuits tuned to the fre uency of theoscillations connected to said control electrodes and said anodes,respectively, and means comprising a transmission line on -shown anddescribed, but that many modifications in the circuitiarrangementa'.

means for regeneratively coupling which standing waves are developed forregen-' eratively couplingthe output and input circuits together wherebythe frequency of the oscillations is held substantially constant.

4. In oscillation generating apparatus, a 5

cathode ray electron discharge device having among the electrodescontained within its evacuated container an electron emitting cathode, aplurality of control electrodes and a plurality of anodes, an inputcircuit connected to the control electrodes and an output circuitconnected to said anodes, said output circuit being tuned to theregeneratively coupling the input and output circuits together, anelectromechanical vibrator and a resonant transmission line coupled tothe input circuit of said device for stabilizing the frequency ofoscillations, said vibrator acting to overcome small variations infrequency and said resonant transmission linelactingto overcome greatervariations in frequency.

5. In oscillation generating apparatus, a cathode ray electron dischargedevice having within an evacuated container an electron emit--tingcathode, a plurality of control electrodes frequency of theoscillations, means for and a plurality of anodes, an input circuitforsaid control electrodes and an output circuit for said anodes, saidoutput circuit being tuned to the frequency of oscillations, meanscomprising a long transmission line long relative to the wave length ofthe working frequency for' regeneratively coupling said input and outputcircuits together and for controlling the frequency of oscillationsappearing in said input circuit.

6. In an oscillation generator,-a cathode ray electron discharge .devicehaving within an evacuated container a plurality of anodes, a pluralityof control electrodes, and an electron emitting cathode, external; meansfor coupling said anodes and control electrodes together,

means for preventing internal feed-back in said device, a crystal incircuit with the control electrodes of said device, and a tunableresonant circuit connected to the anodes of said device.

. 7. In an oscillation generator, a cathode ray electron, dischargedevice having within an evacuated container aplurality of anodes, aplurality of control electrodes, an electron emitting cathode, a tunableinput circuit connected to. said control electrodes, and a tunableoutput circuit connected to said anodes, and atransmission line longrelative to the working wave length coupling said input and outputcircuits of said device for controlling the frequency of operationthereof. 1

8. In apparatus for producing electrical oscillations comprising acathode my type of vacuum tube having a cathode, a plurality of controlelectrodes, and a plurality of anodes, means for suitabh applying anegative potential to said control electrodesand a positive potential tosaid anodes of the tube with respect tosaid cathode, tunable input andoutput circuits connected to said control electrodes and anodes,respectively, and means comprising a transmission line aunultiple of ahalf wave length long.

on which standing waves are generated for regeneratively coupling theoutput and input circuits together whereby the frequency of theoscillations is held substantially constant.

9. An apparatus for producing electrical oscillations comprising" acathode ray type of vacuum tube having a plurality of control electrodesand a plurality of anodes,

means for suitably ap-' plying a negative potential on said controlelectrods and a positive potential on said anodes of the tube withrespect to,the cathode, means to concentrate the electron streamemanating from the cathode, input and output circuits each 5 tuned tothefrequency of the oscillations, means for regeneratively coupling theinput and output circuits, and means independent of said output circuitcomprising a sharply tuned resonant transmission line circuit on whichstationary waves are allowed, to develop coupled to the 4 input of saidoscillator for stabilizing the frequency of the oscillations, and autilization circuit coupled to said output circuit. CLARENCE W. HANSELL.

